Coenzyme Q10, Total
Coenzyme Q10 (CoQ10) is also referred to as ubiquinone because it can be found in almost all eukaryotic cells. CoQ10 embedded in the inner mitochondrial membrane is an essential component of the electron transport chain and plays a role in the ATP-producing oxidative phosphorylation. CoQ10 is also a powerful lipid-soluble antioxidant protecting cell membranes and lipoproteins. CoQ10 is present in the plasma in both the reduced (ubiquinol) and oxidized (ubiquinone) forms. The reduced form of CoQ10 is the only endogenously synthesized lipophilic antioxidant and as such, serves to protect biological membranes against oxidation as well as inhibiting the peroxidation of lipoproteins in the circulation. Reduced CoQ10 in plasma may also have a role recycling vitamin E (alpha-tocopherol).
CoQ10 deficiency syndromes are quite rare and are clinically and genetically heterogeneous. These conditions have been classified into five major clinical phenotypes: . encephalomyopathy; . severe infantile multisystemic disease; . cerebellar ataxia; . isolated myopathy; and . nephrotic syndrome. In some cases, specific mutations have been identified in genes involved in the biosynthesis of CoQ10 (primary CoQ10 deficiencies) or in genes not directly related to CoQ10 biosynthesis (secondary CoQ10 deficiencies.4 Respiratory chain defects, reactive oxygen species production, and apoptosis are variably characteristics of primary CoQ10 deficiencies. Several of these conditions are responsive to CoQ10 administration.
CoQ10 is endogenously synthesized via the mevalonate pathway, and some is obtained from the diet with meat products being the principal source. CoQ10 supplements are available over the counter. Due to its lipophilic nature, CoQ10 is transported in lipoprotein particles in the circulation and plasma levels tend to correlate with serum total and LDL-cholesterol.
Statins lower blood cholesterol levels by inhibiting HMG-CoA reductase, the rate-limiting enzyme in the biosynthesis of cholesterol. This same enzyme is involved in the biosynthesis of CoQ10 through the mevalonate pathway. Plasma CoQ10 concentrations are reduced in patients receiving statin therapy. The magnitude of CoQ10 decline is dose related and can be reversed by discontinuing therapy. It has been postulated that the drop in plasma levels may, in part, reflect by the statin-induced reduction in LDL cholesterol containing particles in the blood stream. The reduction in these lipid particles reduces capacity of the plasma to carry the hydrophobic CoQ10 molecules. Alternatively, the lower plasma levels may reflect diminished synthesis of CoQ10 as the result of statin inhibition of HMG-CoA. A number of studies have reported a drop in the CoQ10 to LDL-cholesterol ratio in plasma after statin treatment. This supports the conjecture that CoQ10 depletion is caused by diminished production as well as decreased LDL carriers
Statins are generally well tolerated. However, their use has been associated with muscle complaints (myopathy) that range from clinically benign myalgia to more serious myositis, and in rare cases, life-threatening rhabdomyolysis. A variety of mechanisms have been proposed to explain statin-induced myopathy with some proposing that the symptoms may be caused by mitochondrial dysfunction resulting from depletion of CoQ10. The results of a recent meta-analysis of available randomized controlled trials do not suggest any significant benefit of CoQ10 supplementation in improving statin-induced myopathy.
CoQ10 supplementation is commonly used in clinical practice in the treatment of patients with chronic heart failure, male infertility, and neurodegenerative disease. Recent findings point to a role of CoQ10 in improving endothelial function in cardiovascular disease. A meta-analysis of clinical trials found that CoQ10 supplementation significantly reduced diastolic pressure in hypertensive patients. Clinical studies are ongoing related to the effectiveness of CoQ10 supplementation in the treatment of a number of neurodegenerative diseases including Parkinson’s disease, Huntington’s diseases and Friedreich’s ataxia. CoQ10 has been found to improve sperm count and motility. CoQ10 treatment has also been found to be useful in other conditions ranging from decreasing the incidence of preeclampsia in pregnancy to mitigating headache symptoms in adults and children with migraine.
Plasma, frozen and protected from light
Green-top (heparin) tube, amber plastic transport tube with amber-top. (If amber tubes are unavailable, cover standard transport completely, top and bottom, with aluminum foil. Identify specimen with patient name directly on the container and on the outside of the aluminum foil. Secure with tape.)
Draw blood into chilled green-top tube. Gently invert five to six times to mix with preservatives. Keep unopened vacuum tube on ice before processing. Immediately separate plasma from red cells by centrifugation. Plasma must be separated from cells within 45 minutes of venipuncture. Transfer plasma specimen to a labeled amber transport tube and freeze on dry ice. Protect from light. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Freeze plasma in plastic amber transport tube with amber-top on dry ice. Protect from light. (Where dry ice is not available at the collection site, the sample may be kept refrigerated or frozen at -20°C for three days, at which time it must be transferred to dry ice for storage. Samples must be shipped to the laboratory on dry ice.)
14 days at -70°C
Use of EDTA anticoagulant;1 specimen not protected from light; plasma not frozen within 24 hours of collection